Abstract
Stationary models are usually applied for wind characteristics analysis. However, nonstationarity has been found in the field measurements of typhoons in recent studies; therefore, using traditional models with stationary assumptions to conduct wind characteristics is inadequate. In this research, data acquisition of typhoon wind speeds and monsoon are conducted based on the wind field measurements. Wind speeds of typhoon “Maria” passing through Pintan, Fujian Province, China and the monsoon from 2017.10–2018.10 were obtained to investigate wind characteristics. The run test method is utilized to show that non-stationarity exists in both typhoon and monsoon wind speed, and the percent of non-stationary increases with the increase in time interval. Additionally, results show that stronger non-stationarity exists in typhoon wind speed compared with monsoons. Based on a self-adaptive procedure to extract time varying mean wind speed, a non-stationary model is established to compare with the non-stationary model, which has been applied in the traditional wind characteristic analysis. The fluctuating wind characteristics such as turbulence intensity, gust factor, turbulence integral scale, and wind speed spectrum are analyzed to compare the two models. Results show that the difference of such characteristics between the two models increases with the time interval, indicating the necessity of consideration of non-stationary models, especially for design specifications with larger time intervals. Influences of time intervals are investigated, and relevant recommendations are provided for wind resistance specifications. Our conclusions may provide reference for wind resistance design in engineering applications.
Highlights
Wind characteristics, especially fluctuating wind characteristics, play an important role in the civil engineering design of high buildings and large-span bridges
Wind characteristics are calculated with the assumption that the fluctuating component of wind speed in a considered time interval is a zero-mean stationary Gaussian random process, and this has been adopted in specifications in many countries
In engineering applications, considering different time intervals, the wind speed is usually decomposed as a sum of the mean wind speed of wind samples and a fluctuating component that is considered a Gaussian stationary random process [9]
Summary
Especially fluctuating wind characteristics, play an important role in the civil engineering design of high buildings and large-span bridges. Numerous techniques have been used to obtain the time-varying mean wind speed, such as the moving average technique [10,11,12,13], discrete wavelet transform (DWT) [14], and empirical mode decomposition (EMD) [15] Their results have shown that wind characteristic parameters calculated by stationary and non-stationary models have large differences. Tao compared two models by investigating wind characteristics from typhoon wind measurements at Sutong Bridge [16] Their results showed that the turbulence intensity and gust factor from the non-stationary model are smaller than those from the non-stationary model. Non-stationary tests are conducted for both typhoon wind speed and monsoon wind samples Wind characteristics, such as the wind profile, turbulence intensity, integral scale, and power spectrum density, are compared from stationary and non-stationary models with different time intervals. The influence of time intervals on the wind characteristics by these two models are investigated as well
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